1. Field of the Invention
This invention relates to diffusion transfer photography. More precisely, the invention disclosed herein relates to diffusion transfer photographic film units or products which can be developed outside of a camera after exposure and can provide a developed, useable negative concurrently with the formation of a positive transfer image pattern.
2. Description of the Prior Art
Copending application Ser. No. 403,037 filed Oct. 3, 1973 now U.S. Pat. No. 3,881,932, issued May 6, 1975, is directed to a photographic film unit suitable for use in photographic diffusion transfer processing wherein a developed, useable negative is formed concurrently with the formation of a positive image. More particularly, the aforementioned copending application is directed to a photosensitive element suitable for use in such a film unit which includes an opacifying system, e.g., a pigment or dye disposed in a polymeric matrix which can provide an effective adherent capability between a pellucid layer carrying a photosensitive layer and the opaque system until the photosensitive element is contacted with a fluid, which will cause swelling of the polymeric material in the matrix. In other words, the polymeric material provides a tight bond to the photosensitive sheet material only in the dry state. Upon swelling, the polymeric material no longer provides an adherent capability and the polymeric matrix separates or can be separated from the photosensitive element.
Copending application Ser. No. 408,374 filed Oct. 23, 1973 now U.S. Pat No. 3,900,323, issued Aug. 19, 1975 is directed to a backing layer particularly suitable for use as the opacifying system for a photosensitive element such as that set forth in the aforementioned application Ser. No. 403,037.
The above-mentioned applications Ser. Nos. 403,037 and 408,374 are herein incorporated by reference in their entirety.
Because of the hydrophilic nature of the polymeric matrix which would provide for its swelling and loss of adherent capability, conditions of high temperature and high humidity may cause blocking between the opaque backing layer and layers of adjacent film units. The present invention is directed to a novel film unit which is not susceptible to the deficiencies of the prior art.